Method of joining a fuel spray nozzle to a fuel manifold

ABSTRACT

A nozzle integrally mounted in a manifold tube which distends in response to internal pressure to vary the flow rate. The nozzle comprises a pintle having a threaded mounting section and a conical seat engageable with the manifold orifice. The mounting section is threaded directly into the manifold tube and the pintle is adjustable by a screwdriver slot to achieve the proper flow setting. A brazing ring is carried by each mounting portion, and all pintles on the manifold are simultaneously secured in position by placing the manifold in a brazing furnace.

I United States Patent [111 3,871,063 Halvorsen Mar. 18, 1975 [54] METHOD OF JOINING A FUEL SPRAY 2,333,968 11/1943 Winter 29/4705 NOZZLE o A FUEL MANIFOLD 2,755,133 7/1956 Conrad 239/534 3,202,513 11/1966 Savage 239/534 [75] Inventor: Robert M. Halvorsen, Birmingham,

Mlch' Primary E.\-aminerA1 Lawrence Smith [73] Assignee: Ex-Cell-O Corporation, Troy, Mich. Assistant Examiner-Margaret M. Joyce Filed: Jan. 18, 1974 Attorney, Agent, or Firm-Harness, Dlckey & Pierce [21] Appl. No.: 434,427 [57] ABSTRACT Related Application Data A nozzle integrally mounted in a manifold tube which [62] Dwslon of 1973 distends in response to internal pressure to vary the 3,827,638. flow rate. The nozzle comprises a pintle having a threaded mounting section and a conical seat engage- UOSI s u [51] [lit- Ci threaded directly into the manifold tube and the pi Fleld of Search C, is adjustable a Screwdriver Slot to achieve the 239/582 proper flow setting. A brazing ring is carried by each mounting portion, and all pintles on the manifold are [56] References Cted simultaneously secured in position by placing the man- UNITED STATES PATENTS ifold in a brazing furnace. 2,145,168 1/1939 Fla 29/4705 2,289,271 7/1942 Kan 29/4705 2 Clam, 4 Drawmg Flglres PATENTEDHARI 8l975 3. 871 63 METHOD OF JOINING A FUEL SPRAY NOZZLE TO A FUEL MANIFOLD This is a division of application Ser. No. 363,055, filed May 23, 1973, now US. Pat. No. 3,827,638.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to fuel spray nozzles of the type used in gas turbines, and particularly the afterburners or thrust augmentors of turbojet and turbofan engines. Conventionally, such augmentors have chambers with fuel spray manifolds extending circumferentially or radially therein. These manifolds are of elliptical cross section and carry a series of nozzles. The invention is particularly concernedwith the nozzle construction.

2. Description of the Prior Art The closest known prior art is illustrated in FIG. 1 which shows the elliptically shaped manifold and a nozzle pintle carried by a pintle support. This construction is made by drilling the two holes in the manifold which are required for each nozzle assembly, and inserting the pintle support in the larger hole at the back of the manifold. The pintle support is then welded into place. After further fine machining, the nozzle pintle is threaded into the support and tightened with a torque wrench against the orifice through which it projects. When the proper setting has been obtained, the nozzle pintle is welded to the pintle support. Upon application of fuel pressure inside the manifold, it will distend to a more circular cross section, its orifice moving away from the conical pintle seat to allow the fuel to discharge against the outer spray deflector and become atomized. The quantity of fuel being discharged depends on the pressure differential between the inside and outside ofthe manifold which varies the size of the annular opening between the pintle seat and the orifice.

The prior art construction of FIG. 1 has a number of important disadvantages. The large size of the pintle support protruding into the manifold causes substantial blockage of fuel flow. Since fuel is supplied to the manifold only at certain points, the pressure loss caused by this blockage affects downstream nozzles with a cumulative effect.

Because of the large hole size needed for the pintle support, the area of the-manifold wall available for distention is greatly reduced, causing the spring rate of the manifold section to become high and incapable of deflecting as far as required for efficient and accurate operation. The manual welding attachment reduces still further the available deflecting'area of the manifold cross section, this reduction varying from one nozzle to another. The weld also introduces a potential fuel leakage point and the possibility of undesirable metallurgical qualities such as weld undercutting, enlarged material grain structures, and strain-aged cracking. Considerable weight is also added to the manifold assembly by the pintle supports and requisite welding, impairing efficiency of the unit in which it is installed. The pintle support also increases manufacturing costs and the complexity of the pintle required.

A further disadvantage of the prior art construction is the requirement for welding the pintle to its support after it has been threaded therein and adjusted. This manual weld varies from pintle to pintle with regard to amount of heat and resulting weld shrinkage, affecting the preadjustment between the nozzle pintle seat and the manifold orifice. This will cause wide variations in fuel flow between individual fuel spray nozzles in a given manifold. The weld also introduces an additional potential leakage point and the possibility of the above described undesirable metallurgical qualities.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel and improved fuel spray nozzle which overcomes the above-described shortcomings of the previous construction, eliminates the need for an intermediate pintle support as well as the requirement for welding and instead provides only the basic essentials of a simple nozzle pintle and manifold assembly.

It is another object to provide a novel nozzle construction of this type which has improved fuel metering characteristics by elimination of the pintle support and its manually variable structural welding.

It is a further object to provide a novel manifold and nozzle construction of this nature which permits a lower spring rate of the manifold section and thus a reduced seat angle for the pintle to provide improved fuel metering accuracy and more equal patternation between the individual nozzles of the manifold.

It is another object to provide a nozzle and manifold construction of this type in which the manifold section spring rate remains more consistent between nozzles due to a non-variable cross section furnace brazing method of sealing the nozzle pintle to the manifold.

It is also an object to provide an improved nozzle and manifold construction of this character which reduces internal flow blockage by eliminating the pintle support and reducing the pintle cross section, thus minimizing pressure drop between nozzles and helping to equalize patternation between nozzles at high fuel flow conditions.

It is a further object to provide a nozzle and manifold construction of the nature which reduces the number of potential leakage points by eliminating the pintle support and its structural weld.

It is also an object to provide a nozzle and manifold construction having the above characteristics, which permits more accurate adjustment of the pintle flow setting by eliminating the manually variable pintle support seal weld that can vary in the amount of weld shrinkage and thus alter flow adjustment.

It is a further object to provide improved nozzle and manifold construction of this type which permits uniform adjustment of all the nozzles in a manifold.

It is another object to provide a nozzle and manifold construction of this character which reduces weight due to elimination of the pintle support and its structural welding as well as reduction in the nozzle pintle size.

It is also an object to provide a novel nozzle and manifold construction which has improved metallurgical qualities by eliminating welding at the individual nozzles, thus avoiding the possibility of weld undercutting, enlarged material grain structures and strain-age cracking. 7

It is a further object to provide an improved nozzle and manifold construction of this character which reduces manufacturing costs by eliminating the pintle support and its attendant manufacturing procedures and through simplification of the pintle construction, thus requiring only a simple threading operation of the manifold and permitting burrs developed by threading to be seen and removed without requiring x-rays.

It is another object to provide a novel nozzle and manifold construction which reduces manufacturing costs by elimination of the pintle support and its complex machining, de-burring and manual welding operations and through simplification of the pintle construction, thus permitting brazing rings to be assembled to the pintle and the latter assembled and adjusted in the manifold segments so that large quantities may be furnace brazed in one operation.

Briefly, the above objects are accomplished by a nozzle and manifold construction in which the manifold of elliptical cross section has a threaded aperture for each nozzle pintle aligned with the pintle orifice. The nozzle pintle has a threaded mounting portion and a conical seat protruding through the orifice. After forming these apertures the pintle is threaded into the manifold, carrying a brazing ring on its threaded portion. It is preset by insertion of a screwdriver and rotation, preferably by supplying pressurized air to the manifold and rotating the pintle to obtain the desired air flow through the orifice. After all pintles are preset, the manifold is placed in a furnace so that all brazing rings seal the pintles to the manifold.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a manifold showing the prior art nozzle and pintle support.

FIG. 2 is a perspective view of the ring type of manifold.

FIG. 3 is an enlarged cross-sectional view showing a nozzle constructed according to the present invention, with the brazing ring in place.

FIG. 4 is a view similar to FIG. 3 but showing the braze seal.

DESCRIPTION OF THE PREFERRED EMBODIMENT A heat-shielded augmentor spray manifold is generally indicated at 11 in FIG. 2, the manifold being shown as ring-shaped with portions of the heat shield broken away and having a pair of diametrically opposed fuel supply connections 12 and 13. A number of these manifolds may be mounted in the afterburner or augmentor section ofa gas turbine. In some cases the manifolds extend radially into the augmentor but the invention is equally applicable to these types of manifolds. Typically, the manifold is fabricated of a stainless heatresisting superalloy such as a nickel-base precipitation hardening alloy containing strengthening elements of titanium and aluminum.

Manifold 11 is of elliptical cross-sectional shape as seen in FIG. 3, with the wider portions of the ellipse forming the front and rear walls of the manifold. The front or inwardly facing wall 14 has a number of fuel ejection orifices 15 formed therein. These orifices have a compound conical shape as seen in FIG. 3, and during operation the pressure of fuel within manifold 11 will cause front wall 14 to distend away from rear wall 16, thus lifting orifice 15 away from the conical seat 17 of a nozzle pintle generally indicated at 18. The annular opening thus created will permit the pressurized fuel to escape from the manifold chamber and impinge upon the reversely conical spray surface 19 of the pintle, atomizing the fuel into a spray cone.

Pintle 18, which may be fabricated of material similar to manifold 11, has a mounting portion 20, a central portion 21, conical seat 17 and spray deflector 19. Section 20 is of relatively large diameter and has an external thread 22. A threaded aperture 23 is formed in alignment with orifice l5 and pintle 18 is threaded therein. Intermediate section 21 of the pintle is of considerably narrower diameter than section 20 and occupies a major portion of the distance between manifold walls 14 and 16.

A drilled lightening recess 24 is preferably formed in section 19 of the pintle, and a screwdriver slot 25 is formed at the outer end of this recess for adjustment purposes.

A preferred method of manufacturing the manifold assembly is as follows: Apertures 23 are drilled and tapped and orifices 15 are also formed in the manifold. The pintles 18 are then threaded into apertures 23 with their seats projecting through the orifices. One way of accomplishing this assembly is to pick up each pintle 18 with a screwdriver or similar tool (not shown) having some means for holding the pintle to the tool blade. The pintle is then manipulated to scoop up a braze ring 26, the internal diameter of this ring having a slight interference fit with threads 22. The pintle is then inserted in aperture 23 with the braze ring staying in place as seen in FIG. 3.

The pintles 18 of manifold 11 or a segment of the manifold, if the manifold is to be fabricated of joined segments, are preadjusted for proper metering. One method of preadjustment is to apply air pressure to the manifold interior and rotate each pintle by a screwdriver inserted in slots 24 to obtain a certain air flow or air pressure drop through the orifice.

After all the pintles have been preadjusted, the manifold or manifold segment may be placed in a furnace so that rings 26 will form a brazed connection 27 (FIG. 4) between manifold wall 16 and mounting portion 20 of the nozzle.

In cases where titanium and aluminum strengthening elements are used in the superalloy, their precipitation may cause difficulty in the wetting action of the base metal during furnace brazing. A preferred method of overcoming this problem is to follow these steps when brazing:

1. Carefully select all tools, lubricants and finishing materials to make sure they do not contain constituents which would inhibit wetting action of the braze filler metal.

2. Place the parts to be brazed in annealed condition to put the gamma-prime compound Ni (Al, Ti) in solution and thus minimize its stop-off action.

3. Just prior to assembly and brazing, clean base metal surfaces by mechanical or chemical means to provide a nickel-rich surface at the interface, assuring maximum wetting action.

I claim:

1. A method for mounting a fuel spray nozzle pintle in a manifold of the type having an elliptical cross section with an orifice in one wide wall thereof, comprising the steps of threadably mounting one end of said pintle directly into the opposite wall of the manifold, rotatably preadjusting the pintle and brazing it to the manifold.

2. In a method for fabricating a fuel manifold and nozzle pintle assembly for a manifold of the type having an elliptical cross section with a plurality of orifices in one wide wall thereof, the steps of threadably mounting said fuel spray nozzle pintles in the opposite wide wall of said manifold with brazing rings thereon, preadjusting said pintles to the proper setting, and placing the manifold in a brazing furnace whereby all the brazing Fings will simultaneously braze the pintles to the maniold. 

1. A method for mounting a fuel spray nozzle pintle in a manifold of the type having an elliptical cross section with an orifice in one wide wall thereof, comprising the steps of threadably mounting one end of said pintle directly into the opposite wall of the manifold, rotatably preadjusting the pintle and brazing it to the manifold.
 2. In a method for fabricating a fuel manifold and nozzle pintle assembly for a manifold of the type having an elliptical cross section with a plurality of orifices in one wide wall thereof, the steps of threadably mounting said fuel spray nozzle pintles in the opposite wide wall of said manifold with brazing rings thereon, preadjusting said pintles to the proper setting, and placing the manifold in a brazing furnace whereby all the brazing rings will simultaneously braze the pintles to the manifold. 